<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>窗口大小事件</title>
    <style lang="">
        div{
            background: #000;
            width: 200px;
            height: 200px;
        }
    </style>
</head>
<body>
    <script>
        //onresize只要窗口大小发生变化，就会触发这个事件
     window.addEventListener('load',function(){
        var div=document.querySelector('div');
        window.addEventListener('resize',function(){
            console.log(window.innerHeight);
            console.log('changed');
            if(window.innerHeight<=700){
                div.style.display='none';
            }else{
                div.style.display='block';
            }
        })
     })
    </script>
    <div></div>
</body>
</html>